Zero-mode TEM parallel-plate resonator for high-resolution thin film magnetic resonance imaging

Abstract

A parallel-plate radio frequency resonator has been designed for high-resolution thin film magnetic resonance imaging. The B1 field produced by the resonator was evaluated through experiment and numerical simulation. The resonator, composed of two conductive plates sandwiching the sample, generates a uniform B1 field parallel to the plates. This feature renders the resonator largely immune to radio frequency screening from conductive layers parallel to the sample. The resonator is custom fabricated according to the dimensions of the sample, yielding a high filling factor. The radio frequency probe is shown to facilitate high-sensitivity depth profiling of thin films. Three variations on the basic design are examined. Since the intention is to employ these resonators for functional studies of membranes, we introduce perforations in the parallel plates to permit mass transfer in and out of the thin films under study. One-dimensional depth profiles of Nafion 117 are presented with and without the addition of additional plates of conductive material. One-dimensional depth profiles of Nafion 1110 and a two-dimensional image of Nafion 117 in an operating fuel cell, which was integrated into the radio frequency circuit, are also illustrated.